C /3 U52 



61sT Congress, [ HOUSE OF REPRESENTATIVES. \ Document 

3d Session. \ [ No. 1329. 



PRESERVATION AND REPAIR OF CABIN JOHN BRIDGE. 

F 189 

.C13 

U52 LETTER 

Copy 1 

FROM 

THE ACTING SECKETARY OF THE TREASURY, 

TRAXSMITTIN(; 

A COPY OF A COMMUNICATION FROM THE BOARD OF COMMIS- 
SIONERS OF TKE DISTRICT OF COLUMBIA SUBMITTING AN 
ESTIMATE OF APPROPRIATION FOR AQUEDUCT AT CABIN JOHN 
BRIDGE. 



January 30, 1911. — Referred to the Coininittee on Apprnpriatiorif: and ordered to Ije 

printed, with ilhistratioiis. 



Treasury Depart.^iext, 

JanMan/ 28, 1911. 
Sir: I lia\e the honor to trunsmit herewith, for the eonsideration of 
Congress, copy of a conininnication of the president of the Board of 
Commissioners of the District of Columbia, of this date, submitting 
an urgent estimsite of appropriation recommended by the Chief of 
Engineers, United States Army, and transmitted through the Secre- 
tary of War, re([iured for the \\^islungton Aqueduct for the preserva- 
tion and repair of Cabin John Bridge, ^35.000. of which the sum of 
$lH),00(» is to be inmiediatidy avaihible. 

It appears that extensive leakage has developed at Cabin John 
Bridge, which carries the Washington A(iueduct across a deep ravine, 
and that the condition is serious, which explains the necessity of sub- 
mitting this estimate at this time. 

Respectfully, C. D. Hilles, 

^•1 ct 111 (J Sevi'ttary. 
The Speakku of the House of Rkpresentatives. 



Office Commissioners of tup: 

District of Columbia. 
W<(shuigto)u Jan vary .AV, 101] . 
Sir: The Commissioners of tlie Disti'ict of Columbia iiave the honoi' 
to transmit herewith a sup))lemental estimate of ai)propriation needed 
for the Washino-ton Atuieduct for th(^ liscal vcar to (md June oO. \\)V1. 



^ I'KKSKKVATK.N AND KKI'AIK ..K CAHIN ..,.11N HKII)(;k. 

<..• am;';:i';u;?:;"to';;;j;"n^ •'"''i^ '^'•■*^^? -i-ii"^'i.e installation 

;;;::::;s;:;;^fna^r^---^ 

1..Hos(mI with this cstinrnt. i. th.> h-tter of th. connnissionrrs datod 
- tl msta„t. tnu.sni.ttmo- it to tho PresichM.t of (ho rnit.MrStato 
(.1 Ins a fon as per your letter of i.istruHion of th. -^Nt ul i u> u d 
hcaiino- tho Presidout's approval. " ninino. .md 



s app 
\ (TV rospectfiillv. 



HOAKI) OK roMMISSH.NKUS. DisTlM. I OK (<„,i:Mr..A, 

l>.\ ( I No II. K'i;i)oi,i>ii. 



lion. Fk'anki.tn Mr\'KA(iii, 

Sr,r,i((rij of //tr 'I'l'iiisni'tl. 



■mw .>(J, in.. Ihi th,- ( <niimissn>,„'rs uj llir DIslrirt nf Cnhniihiu. ■ 

IIISTHKT OK (OLTMlilA. 

W ;isliiii^r(,,ii AijiK'diict: 

Fur tJ.e preseryatio.. and repair of Cabin .lohn Bri.I-.., in,-lu,iin.. th,> 
'-•: :',;?';'" « ^^ '"f ' ""'".- ^" i'>-'"vent l<.aka.e in the r H' • 

\ 1.1. nj,t(.n A.,ne.n.t passu,,, tluon^h the l.H<li,e, of uhirh S2( ( i 
^hall he nnmediately availahle (snl.nutte.i. VoL 20, p. ]()4, see 'i) s;^.",, (,„o 
XoTK.-8ee accouipanyinu lettrr ,.f (ransniittal ainl its inciosurcs. 



I AM- \l;v 2(>, l!»l i. 



('(NO H. Rii)()i,i>n, 

•lollX A. .JOHNSTON, 

\y . y . jiosox, 

Coiiniiis.'iioii,,:'^ of th,' Di.^/rirt of (),lin,il,hi 



I'mtki) Statics Encinioki; Oikki:. 

!>i^o Skvf.ntekxtii Stimoet N\\'.. 

]\(i.s/n',,<jf,>ii, /}. C. JiUnHin/ Jl, V.ni 
Mk. I have (he honor tosul.init the followino- item for\raMsmissioM 
Mirough the re.i(ular channels to the proper comniittce of Conoress for 
insertion as an amendment t(, the District appropriatio., hiirfor the 
hs<.al y''=i'- l!»l^, which IS und(M-stood to have been ivported from the 
committee to the House oi Representatives on -lanuarv IS l:»ll ,),• for 
|)assao-(> as a sju'cial bill or joint resolution: 

2. Cabin John P>rid,oe is one of the noted cnoi„.>erino- structure^ 
bcin.^. until ]!»()2. the lon-est cut-stone masonrv aicJi" s,)an in the 
world It was .•ompleted in ksc:}. since which date it has served to 
carry t.(>, water supply of the city comino- from the (livut Falls of 
the 1 otomac, across th(« deep ravin(^, at Cabin John Run. about M 
tniK's Irom the District line. The a(|uedm-t at this point is one of the 
weakest points in the system, as an interruption bv the breakino- of 
the conduit at this brido-e would be verv ditiicult to repair in the short 
time p(M-nntted l)y the limit(Ml stora.ov supply of wat(M-. The prcserva- 



PRKSERVATTOX AND KKI'AIK (>K (WHIN .lOHN HRllKiK. 8 

tion, therefore, of Cabin -lolm Bridg-e is esscntiul to the permanence 
of the water supply of the District, an interruption at this point 
beino- likely to cause a shortage or a failure of the supi)ly in the city. 

3. U'hen the watcn- was first admitted to the conduit" from Great 
Falls, in 186^, a number of leaks were found in the Cabin .John Biidoe 
when thei-e was at)Out T feet of water in the conduit, which is 9 feet 
in diameter. The water was drawn otf. the lower half of the conduit 
was plastered, and after the water was again admitted to the conduit 
no leakage was observed, the ilow Wuv l)eino- Ixdow (he upper limits of 
the plastered section. 

4. As the consum])tion of \\at<M- in the city has increased, i-etpiiring 
the extension and raising of the (him at Great Falls, the conduit has 
been running fuller until the comj)letion of the dam at Great Falls to 
its present elevation caused the hydraulic gradient at ("abin -lohn 
Bridge to be altout 2 feet ab()\ c the ciown of the conduit when the 
Dalecarlia reservoii- was full. The u])per portion of the conduit 
through the bi'idge not having been phisteied. it was notiul in JIM).") 
that th(^ water had worn away th(^ mortar betweim the bricks to a 
depth in some places of an inch or more. 

5. As the amount of water passing through tiuM-onihiit increasinl. 
causing a greater depth in the conduit over tlu» l)ridge, the leakage in 
the bridge began again, and in liM),> the interior was carefully cleaned 
and ail visible cracks were Hlled with cement moi'tar. The anmial 
report of the otiicer in charge, for the tiscal year iDOtJ, rei)orts that 
about 90 per cent of the leakage was stopped by this pjastiu-ing. 

t). Fxperiments were started at this time to det<M'mine the l)est 
means to remedy the defects. Believing that nuich of the leakage 
through the bridge occurred through the mortar joints of the brick in 
the unplastered upper portion of the conduit, the plastering of this 
part of the conduit in the bi'idge was commenced in the tiscal vear 
1908. At the end of the tiscal year 1909, i:i4 feet of the :)T0 feet of 
the conduit through the bridge was completely plastcMvd with Portland 
cement mortar. As this did not noticeably atl'ect the leakage, etforts 
were made to push the work of plastering to completion. This work 
was completetl late in the tiscal year 191<». and ap])eared to stop the 
leakage at the middle of the bridge, but did not materially affect the 
leakage between the middle of the bridge and the abutments. 

7. During inspections long cracks in the masonry of the conduit 
within the bridge were noted on both sides of the center of the bridge, 
the axis of the bridge lying almost due east and west. These cracks 
weie kept carefully tilled with cement mortar, and it was not until the 
conduit through the bridge was completely plastered that those in 
charge of the a(iueduct felt assured that most of the leakage did not 
come through the mortar joints of the brick crown of tlie conduit. 
These long cracks lie in the lower (|uadrant of the conduit on the north 
side of the l)ridge. and undoul)t<Mlly ha\e been caused by the une(|uai 
expansion of the two sides of the bridge, the south side l)eing exposed 
throughout the day in the sununer to the direct rays of the sun. while 
the north side of the bridge is nearly always in the shade. This un 
e((ual ex{)ansion h:is broken the brick rings of the conduit along the 
length of the cracks, and the ui)per (|uadrant of the ring is moving 
over the lower ([uadrant at the rate of one-eighth of an inch a ye;ir. 
as determined by recent measurements. If tins action is permitted to 
s-o on it is tikelv that the rate of this movement will be accelerated 



I'RKSKI{VA rio.N AM) IJKI'AIli <»K CAI'.IN -loHN liRllXJi:. 



Ciicli ycjir uiilil llic tiiial t'liilin'c ol' (lie ((jiiduit In (•()lla])se. A> the 
iiiitsomv in the brido'c contracts duriiij^- cold wcatlKT the cracks in tlio 
conduit i)])(Mi. t lie extent of I lie opcninii' depending:' to sonic extent upon 
the dej^Tee ot' cold. 

s. In the sununer. under pcesent conditions, the water leaks through 
the joint> in the niasoni'v >i(ie walls of the hridoc ;ind passes down 
ov'ei' the i'ace of the hi'idy'e to the ^^round l)(do\\. In the winter, the 
watef ri'ee/ino- to some extent in the joints ol" the niasoni-y on the out- 
side of the l)i-i(|o-e. much of the leakaji'c i)ass(vs down the insiih' of tiie 
Itridue I hrouoh the hoHow abut ments and thence through the dooi'- 
ways in the side walls of the ahutments. (See photoo-raph appended.) 
The condition of the extei'ior of the l>i'ido-e i< shown in the photo 
i4"i'aphs appended hei'clo. taken on I )ecend)er 2i\ iH|i>. which indicate 
to some extent the leaka^^e from the l»iidu(« diirine- the cold weatluM' 
of the ndddle of i)ccend>er. It lia> Ikmmi t'stimated that the leakaLi'e <d' 
water through the masonry of the l)iido-e at the latter date was not 
less than I'.OOd.tMiO t^-allons of \\atei' per day. The maximum ca))acity 
of the conduit is IKi.dOd.dOd gallons per day and the axerau'e annual 
corismnption is alK)ut <>i!,<iO(i,(i(i(> o-allons ])er day. 

;». It isl)(die\cd thai the condit ioti is so sei'ious that the application 
of the neces>ar\ reme(ly should he no louLj'er |)Ostponed. At the time 
of the suiimissidii of th(^ estimates in the annual re|)ort fi'oni this 
ollice il was i-eali/.t'd that ixM'manent repairs would soon he necessary, 
hut estimate^- were not (hen sul)mitted because the manner of repair 
ine the liridiif in the most economical and jn'riuanent mannei' liad not 
then heen delcmuned. It is now proposed to place within the hridoc 
a metal lininj^- eil her of a steel or iron tube S fei't ('■> inches in diameter, 
sunounded l>y conei'ete. or l»y the })lacinL;of cast-iron sectional lining'. 
N feet in diameter, similai' to that used in the W'ashinn'ton .\(|ueduct 
tunnel under Ivock ('reek. I'jiher method would l)e satisfactory and 
would ri'iiderthe l)ri(l^-e water tiu'ht. thus pre\ cut ini;- t h(> disinteui'a 
tion of the nia>onry in the face of the hri'ly-e, caused hv the free/in^' 
of ihe wat(M- in the joints and interst ice->. and would check the deteri- 
oration of the conduit now in proui'cs^. 'Vho j)lan ado|)ted would de- 
pend up(m the prictvs received for furnishine' th(> materials necessai'y 
undei' the two methods, and also upon the conxcnience of instadation 
with the least interruption to the water su|)ply. 

!". iJeducine- tlie diameter of the MU^ feet of conduit throueh the 
liriilet' to s feet I'l inches. oi- to ^ i'(H^t. would tend to increase* the los> 
of head at maxinnun rate of How <>.7 inch, or l.i' inches, respect i\'tdy. 
The ^toppniLi' of the leakae'e would tend to I'cduce tin* loss of luMd 
about ! inches. Thei'id'ore. the linal etl'cct of I'cpairs to the bridec 
would be to reduce (he loss of head by about .'i.:! inches for a diameter 
of S feet il in:he>.. or about l'.s inches \\<v a iliamet(M' oi' s feet, at the 
maxinmm rate <d' flow in the conduit. The total loss of head between 
(ireat !''alU ;ind Halecarlia Keservoir. at maximum rate of llow. i^ 
about 7 feet ',» inche>. 

!1. The ne(C->sity for ihi> work is consitlered -^o urecnt that the 
estimate o\' -Sl.^.doit. as noted at)o\e. is sul»nntted at this time with a 
\'iew to lia\ine- a portion of the estimat»'d amount made iimueiliatelv 
a\ail'ible. -o that th(> work may be lieeam at once. 
\'ei-\ re>peci fully . 

\\ . ('. Lanoi 11 1. 

The ( 'iiii'.i' (»K 1\N(.1M'.K Us. r. S. Akmv. 

ir-/.v/////,//o,,, /). c. 



PRESEKVATION AND HKPAIK OF ('AHIN -iniiN URIIX,!;. 

[I'irst )iiilor>eniciU.j 







A\'ai; I)kpai!t:\iknt. 

Ol'^KlCK OF THK ClllFF OF Kn(;IXKKKs. 

^y<ls/,|,,</fon. 'J I 111 mini i'^. lUll, 

1. Respectfully siihiiiittod to \\w Secretarv of War. 

'1. The office in cliaro-e of the Washinotoii Aquoduct rcijort^ that 
extensive leakag^e has developed at Cabin John Hi-ido-e which carries 
the aqueduct across the deep ravine at Cahin John Knn. Md.. and 
states his belief that the condition r- serious. '\\w Chiof of Knuineers 
concurs in this opinion and reo-ards (he riMnedv proposed as of'lii-oent 
necessity in order to check th(> present h>aka,o-e, nnd aveit the dan»-er 
of the destruction of the conduit, and \\w c()nse(|uent complete stoppao-e 
of the water supply of the city of Washington. It is therefore reconi 
mended that this report and the acconipanvin^- i)hot()o-raphs be trans- 
niitted to the Commissioners of the District of Columbia, recommend- 
ing the insertion of an item in the peiuliiio- District of Columbia 
appropriation bill substantially as follows: 

For the preservation and repair of ('al)in .lolin Hridue, inclndiiiif the in^tal!atioll of 
a metal lining to prevent leakage intlie portion of the Washington A(|ne(hiet pas-in<>- 
through the bridge, thirty-live thousand dollars, of wliich Iwentv t!iou<and (h.Hars 
shall l)e iraniediatelv available 

W. 11. Ih.xp.v. 

('/I'cf "f hlKJ'lK 'Vs. f^iiifxl S/tlfrS J/V/'//. 

fSi'ciiiKt iii(liirsciin'ii"i.] 

WaI; DEl'AIiTMKXT, 

J<n>iiiini ?.;. 7.97/. 
Kesi)ectftdly transmitted to the Commissioners of the Distrit-t of 
C|olumbia, requesting action recommended l)y the Chief of Knoineers. 
United States Army, in the preceding indorsement. 

J. M. Dickinson . 

S, ii-rtory if ll'/r. 

O 




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LIBRARY OF CONGRESS 



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